This invention relates generally to plunger pumps or like pumps for fluid and mixed fluid and semi-solid pumping systems, and more particularly to a seal and stabilizing arrangement by which a packing gland assembly limits leakage from the pump. The packing gland assembly also adds rigidity to the pumping element being sealed by a packing and a seal. An eccentric bearing liner made of a low wear and lubricated material decreases maintenance and wear, and is also an environmentally friendly alternative. Together, the packing gland assembly and eccentric bearing liner provide for a cleaner operating pump, approaching xe2x80x9cleak-freexe2x80x9d status, which requires less maintenance and care than existing assemblies.
The use of xe2x80x9cpackingxe2x80x9d in pumps and other apparatus having reciprocating, slidable or rotatable members for moving fluids or mixed fluids and semi-solids is well known. Packings are typically made up of a resilient or at least compressible material which serves a sealing purpose through its compression and retention of a lubricant, most often an oil or graphite. Rough adjustment of the degree of compression is possible and often necessary on a periodic basis, the adjustment being made typically through the tightening of the member (referred to as a packing gland in a plunger pump) which holds the packing in compression. (Reoiling is sometimes necessary on a periodic basis, the oiling usually applied manually).
Generally, it has been accepted that the packing wears during the operation of pumps and other apparatus utilizing packing in such fluid pumping systems. Thus, leakage occurs around the packing which causes a loss in volumetric capacity of the systems. Moreover, the fluids, often containing undesirable and potentially hazardous components, spill into the vicinity of the pump and overall fluid-moving apparatus. In a plunger pump, the packing gland is made of cast metal and is held to the cast iron plunger housing by bolts. In order to hold and compress the packing in the stuffing box, the gland is tightened down by the bolts to further compress the packing in the stuffing box. Eventually, the packing is no longer effective and must be replaced. To prolong the life of the packing, and avoid the time-consuming replacement of it, a lubricant is often freely applied.
The assembly of the packing gland typically leaves wide clearances, particularly since the packing gland is cast and the housing and plunger are cast. Therefore, as the plunger moves up and down in a plunger pump, or the pumping element moves otherwise in other pumps, there is often a continuous horizontal shifting of the plunger. This leads to increased wear, sometimes creating an xe2x80x9chour-glassxe2x80x9d shape instead of a cylindrical shape, and increased leakage.
Another area of the plunger pump or like pump which requires maintenance and care is the bearing for the eccentric, which is the expedient that allows for pump stroke and capacity variations. In a plunger pump, the eccentric is housed above the plunger and carries the plunger, via a connecting rod, through a particular pump stroke. The bearing used between the eccentric and the connecting rod is typically a Babbit bearing. The bearings are recognized as a wear item, and are oiled by associated and messy mechanical oilers. Eventually, the liner must be replaced, and this must be done at the expense of operation time. Also, disposal of the liner poses a hazard, as does the oil from the mechanical oiler which must be used to care for the bearing. The use of oil also risks possible contamination of the fluid that is being pumped, and can thus cause an environmental hazard.
In general, the industry has accepted the leakage and maintenance problems associated with plunger pumps and the like pumps. Great effort has not been made to alleviate the shortcomings which have simply been tolerated over the years. The silence of advances in this area must be broken.
The present invention relates more specifically to a pump with a housing and a pumping element disposed for movement within the housing so that liquid can be moved through the pump. A packing and a seal are associated with the pump housing and the pumping element for sealing the pump from the loss of liquid. A packing retention element retains the packing and the seal in position for their sealing function. A stabilizing element is disposed on the side of the packing remote from the interior of the pump housing. The stabilizing element bears against the pumping element during movement of the pumping element and facilitates stabilization of the same.
Preferably, a scraper is provided that filters grit and sand and other debris to prevent it from entering the stuffing box and reaching the seal and causing damage to the seal, stabilizing elements and packing.
Preferably, a second stabilizing element can be provided on the side of the packing which is adjacent to the interior of the pump housing, in order to provide for further stabilization of the pumping element. The clearance between the stabilizing element and the pumping element is preferably about 0.005 inch and the clearance between the second stabilizing element and the pumping element is about 0.005 inch.
In a preferred embodiment, the second stabilizing element is twice the size of the stabilizing element.
In a preferred embodiment, the stabilizing element is made at least partially of acetal material.
In the embodiment having a second stabilizing element, such second stabilizing element is preferably made at least partially of acetal material and is twice as big as the stabilizing element. The second stabilizing element may also be made at least partially of acetal material.
In another embodiment, the stabilizing element and the second stabilizing element are made at least partially of polyetheretherketone.
Preferably, the seal and the scraper are made of UHMW polyethylene.
The pump in one embodiment is a plunger-type pump wherein the pumping element is a plunger which reciprocates within the pump housing. The packing retention element is a packing gland which is connected to the pump housing.
Preferably, at least one adjustment stud is provided with respect to the packing retention element and the pump housing. The adjustment stud provides for the adjustment of the force supplied to the packing and the seal by the packing retention element to thereby increase the sealing efficacy of the packing and the seal. The adjustment stud preferably includes a stabilizing section associated with the packing retention element, the stabilizing section permitting movement of the packing retention element in a first direction, often vertical, and to limit movement of the packing retention element in a second direction, often horizontal. Preferably, the adjustment stud also includes an adjustment section which provides for the adjustment of the packing retention element in the first direction.
In another embodiment of the present invention, the pump housing includes an area for receiving the packing retention element and a threaded opening therein. The adjustment stud has a first threaded portion which threadedly engages a threaded opening in the receiving area. The adjustment stud preferably includes a shoulder between the first threaded portion and the stabilizing section. The shoulder being provided to engage a stop surface in the receiving area, whereby the adjustment stud is rigidly attached to the housing. Preferably, a plurality of adjustment studs are provided and the packing retention element includes a plurality of stud openings through which such plurality of adjustment studs can be provided. Also, it is preferable that the stabilizing sections of the studs be smooth.
Preferably, the adjustment sections of the adjustment studs include a second threaded portion and a sleeve portion bearing on the packing retention element. The second threaded portion is remote from the first threaded portion. An adjustment nut is provided on the second threaded portion for adjustably forcing the sleeve portion onto the packing retention element in order to facilitate the sealing function of the packing.
Preferably, a dry film lubricant is provided on the packing to facilitate the sealing effect of said packing and permit smooth operation of the pumping element.
In addition to the stabilizing element, the pump can be a plunger-type pump operated by an eccentric connected to the plunger by a connecting arm, and further including an eccentric liner which is highly resistant to wear. Preferably, the eccentric liner is made of reinforced Teflon such as RULON sold by Saint Gobain of Bristol, R.I.
The present invention also relates to a pump for pumping liquid, the pump having a housing with an interior, a pumping element for movement within the housing, a seal and a packing associated with the pump housing and the pumping element to seal the pump from the loss of liquid from the interior of the pump housing. A packing retention element can be provided for applying a force to the packing and the seal from the side of the packing and the seal remote from the interior of the pump housing. A stabilizing element can also be provided for facilitating the stabilization of the pumping element. The clearance between the stabilizing element and the pumping element is preferably 0.005 inch. Preferably, the above pump further comprises a scraper for protecting the seal and packing from sand and grit. In addition, the pump comprises a second stabilizing element for providing further stabilization of the pumping element. In a preferred embodiment, the clearance between the second stabilizing element and the pumping element is about 0.005 inch.
Preferably, the second stabilizing element is twice the size of the stabilizing element.
In a preferred embodiment, the stabilizing element and the second stabilizing element are at least partially made of acetal material.
In a preferred embodiment, the stabilizing element and the second stabilizing element are at least partially made of polyetheretherketone material.
Preferably, in the above pump, the scraper and seal are made of UHMW polyethylene.
The above pump may be a plunger-type according to another aspect of the invention, a pump is provided for pumping liquid. The pump has a pump housing having an interior, a pumping element for movement within the housing, a packing element associated with the pump housing, and a stabilizing element to facilitate the stabilization of the pumping element during its movement. Preferably, the clearance between the stabilizing element and the pumping element is in the range of about 0.008 inch to 0.010 inch.
Preferably, the above pump further includes a second stabilizing element for further stabilization of the pumping element during its movement. The clearance between the second stabilizing element and the pumping element is preferably in the range of about 0.008 inch to about 0.010 inch.
In another aspect of the present invention, a kit is provided for retrofitting an already existing plunger type pump having a pump housing, a stuffing box and packing therein. The kit includes a gland for exerting a force on the packing, a stabilizing element having an annular shape and being constructed and arranged for disposition above the packing, an adjustment stud for adjusting the force exerted by the packing gland on the packing. The adjustment stud includes a stabilizing section which permits vertical movement of the packing gland and limits horizontal movement of the same, and further includes a first threaded portion for threading into existing bolt holes in the plunger housing. It further includes a second threaded portion above the stabilizing section and an adjustment nut threadingly associated with the second threaded portion and a sleeve disposed around the second threaded portion and between the adjustment nut and the packing gland in assembled condition. In a preferred embodiment of this aspect of the invention, a secondary stabilizing element having the annular shape and being constructed for disposition below the packing is provided. In addition, in a preferred embodiment, the stabilizing element and the packing gland are integrally formed as a single element, and that single element is made of nylon. In a preferred embodiment, the secondary stabilizing element is made of UHMW polyethylene.
In another aspect of the present invention, a method of installing a sealing and stabilizing assembly is provided. The kit described generally above is used, and the method includes the steps of placing the secondary stabilizing element below the packing, if it is part of the kit, placing the packing in place above the secondary stabilizing element if it is provided, placing the stabilizing element and the packing gland above the packing, installing the adjustment stud through a hole in the packing gland, tightening the stud until the stud bottoms out on the plunger housing, and adjusting the force exerted against the packing by turning the adjustment nut.
Accordingly, it is an object of the present invention to provide stabilizing elements on at least one side of a stuffing box to facilitate the stabilization and sealing of the pump at the intersection of the pumping element and its housing.
It is another object of the present invention to provide a seal and a scraper made of material highly resistant to wear to prevent liquid from leaking out of the pump.
It is another object of the present invention to provide such stabilizing elements in conjunction with the packing gland, and a further object to make such packing gland and stabilization elements, together with the packing, adjustable.
It is another object of the present invention to provide an adjustable packing gland assembly to control and limit leakage through packing used in fluid pumping systems.
It is another object of the present invention to provide an adjustable packing gland assembly which enables the packing gland to tighten the packing more evenly, minimizes overtightening and uneven pressure forces on the packing as it is tightened and prevents premature wear of the packing and plunger.
It is another object of the present invention to provide an adjustable packing gland assembly which also adds rigidity and support to a reciprocating, slidable or rotatable element being sealed by the packing, thus reducing wear and potential hour-glassing of the walls of the element and wear of other pump elements.
It is another object of the present invention to provide an adjustable packing gland which is adapted for retrofitting in existing pumping apparatus.
It is another object of the present invention to provide an eccentric liner which is made of a material highly resistant to wear, and a further object to provide such material having lubricity to facilitate the smooth operation of the eccentric of a pump.